What is the smallest number of shaded squares that must be added so that the lines AB and CD are both lines of symmetry ?
(A) 2
(B) 3
(C) 4
(D) 6
What is the smallest number of shaded squares that must be added so that the lines AB and CD are both lines of symmetry ?
(A) 2
(B) 3
(C) 4
(D) 6